An example of variable valve mechanisms of internal combustion engines is a variable valve mechanism 90 of a conventional example shown in FIG. 12 (Patent Document 1). The variable valve mechanism 90 is a mechanism that drives valves 8 of a plurality of cylinders 6 arranged side by side in a linear direction. The variable valve mechanism 90 includes a plurality of swing members 91 arranged side by side in the linear direction. Each swing member 91 includes an input member 92, output members 93, 93, and a slider gear 94 that meshes with the input member 92 and the output members 93, 93 via helical splines H. When the input member 92 is driven by a cam (not shown), the swing member 91 swings to drive the valves 8, 8 by the output members 93, 93.
This variable valve mechanism 90 further includes a variable device 97. The variable device 97 includes a control shaft 98. The control shaft 98 extends in the linear direction (the direction in which the swing members 91 are arranged side by side), and is displaced in the linear direction together with the plurality of slider gears 94. The variable device 97 displaces the control shaft 98 in the linear direction to displace the plurality of slider gears 94 at a time with respect to the plurality of input members 92 and the plurality of output members 93, thereby similarly changing the valve lifts of the plurality of swing members 91 at a time by meshing of the helical splines H.